Title: A parameter design of CNC plasma-arc cutting of carbon steel plates using robust design

Authors: John Kechagias, Michael Billis, Stergios Maropoulos

Addresses: Department of Mechanical Engineering, Technological Educational Institute of Larissa, Larissa 41110, Greece. ' Department of Mechanical Engineering, Technological Educational Institute of Larissa, Larissa 41110, Greece. ' Department of Mechanical Engineering, Technological Educational Institute of West Macedonia, Kozani 50100, Greece

Abstract: An optimisation of the cutting parameters during CNC plasma-arc cutting of St37 mild steel plates is attempted using robust design. The process parameters tested were plate thickness, cutting speed, arc ampere, arc voltage, air pressure, pierce height, and torch standoff distance. An orthogonal matrix experiment [L18 (2¹ × 3⁷) ] was conducted and the right bevel angle was measured and optimised according to the process parameters using an analysis of means and an analysis of variances. The results show that the arc ampere has an effect mainly on the bevel angle (50.89%), while the plate thickness and torch standoff distance also have an influence of 6.22 and 15.9% respectively. The other parameters have an F factor smaller than one, and thus their variations do not significantly affect the bevel angle in the experimental region. Finally, an additive model was applied on the experimental results to predict the optimum combination and was compared with actual values.

Keywords: CNC plasma-arc cutting; PAC; carbon steel plates; robust design; parameter design; process optimisation; experimental design; plate thickness; cutting speed; arc ampere; arc voltage; air pressure; pierce height; torch standoff distance.

DOI: 10.1504/IJEDPO.2010.034988

International Journal of Experimental Design and Process Optimisation, 2010 Vol.1 No.4, pp.315 - 326

Published online: 31 Aug 2010 *